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I've known about supervisor ever since Chris McDonough's PyCon 2008 talk. I've wanted to use it before, especially in conjunction with mysql-proxy, but my efforts in running it haven't been met with success. That is, until I realized the one but important mistake I was making: I was trying to run mysql-proxy in its own --daemon mode, and I was expecting supervisor to control the mysql-proxy at the same time. Well, this is not how supervisor works.

Supervisor handles processes that run in the foreground, and it daemonizes them for you. It knows how to capture stdout and stderr for the process it controls and how to save those streams either combined or separately to their own log files.

Of course, what supervisor excels at is actually monitoring that the process is running -- it can detect that the process died or was killed, and it will restart that process within seconds. This sounds like the perfect scenario for the deployment of mysql-proxy. Here's what I did to g…

Munin doesn't ship with a memcached plugin. Almost all links that point to that plugin on the Munin wiki are broken. I finally found it here. Here's what I did to get it to work:Download raw text of the plugin. I saved it as "memcached_". Replace @@PERL@@ variable at the top of the file with the path to perl on your system. Make memcached_ executable.On the munin node that you want to get memcached stats for (ideally you'd add these steps to your automated deployment scripts; I added them in a fabric file called fab_munin.py):Copy memcached_ in /usr/share/munin/plugins (or equivalent for your system)Make 3 symlinks in /etc/munin/plugins to the memcached_ file, but name each symlink according to the metric that will be displayed in the munin graphs:ln -snf /usr/share/munin/plugins/memcached_ memcached_bytesln -snf /usr/share/munin/plugins/memcached_ memcached_countersln -snf /usr/share/munin/plugins/memcached_ memcached_rates Install the Perl Cache::Memcached modu…

Rightscale recently published a whitepaper titled "Load Balancing in the Cloud: Tools, Tips and Techniques" (you can get it from here, however registration is required). I found out about it from this post on the Rightscale blog which is a good introduction to the paper. Here are some things I found interesting in the paper:they tested HAProxy, Zeus Technologies Load Balancer, aiCache's Web Accelerator and Amazon's Elastic Load Balancer (ELB), all deployed in Amazon EC2the connection rate (requests/second) was the metric under test, because it turns out it's usually the limiting factor when deploying a LB in the cloud it was nice to see HAProxy as pretty much the accepted software-based Open Source solution for load balancing in the cloud (the other LBs tested are not free/open source)the load testing methodology was very sound, and it's worth studying; Brian Adler, the author of the whitepaper, clearly knows what he's doing, and he made sure he eliminate…